// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/zone/accounting-allocator.h"

#include "src/allocation.h"
#include "src/base/logging.h"
#include "src/zone/zone-segment.h"

namespace v8 {
namespace internal {

    AccountingAllocator::~AccountingAllocator() = default;

    Segment* AccountingAllocator::AllocateSegment(size_t bytes)
    {
        void* memory = AllocWithRetry(bytes);
        if (memory == nullptr)
            return nullptr;

        size_t current = current_memory_usage_.fetch_add(bytes, std::memory_order_relaxed) + bytes;
        size_t max = max_memory_usage_.load(std::memory_order_relaxed);
        while (current > max && !max_memory_usage_.compare_exchange_weak(max, current, std::memory_order_relaxed)) {
            // {max} was updated by {compare_exchange_weak}; retry.
        }
        DCHECK_LE(sizeof(Segment), bytes);
        return new (memory) Segment(bytes);
    }

    void AccountingAllocator::ReturnSegment(Segment* segment)
    {
        segment->ZapContents();
        current_memory_usage_.fetch_sub(segment->total_size(),
            std::memory_order_relaxed);
        segment->ZapHeader();
        free(segment);
    }

} // namespace internal
} // namespace v8
